Transgenic Adenocarcinoma Of The Mouse Prostate Research Articles

Characterization of tumor-associated macrophages in prostate cancer transgenic mouse models.

Tumor-associated macrophages (TAMs) are critical components of the tumor microenvironment (TME) in prostate cancer. Commonly used orthotopic models do not accurately reflect the complete TME of a human patient or the natural initiation and progression of a tumor. Therefore, genetically engineered mouse models are essential for studying the TME as well as advancing TAM-targeted therapies. Two common transgenic (TG) models of prostate cancer are Hi-Myc and transgenic adenocarcinoma of the mouse prostate (TRAMP), but the TME and TAM characteristics of these models have not been well characterized. To advance the Hi-Myc and TRAMP models as tools for TAM studies, macrophage infiltration and characteristics were assessed using histopathologic, flow cytometric, and expression analyses in these models at various timepoints during tumor development and progression. In both Hi-Myc and TRAMP models, macrophages adopt a more pro-tumor phenotype in higher histological grade tumors and in older prostate tissue. However, the Hi-Myc and TRAMP prostates differ in their macrophage density, with Hi-Myc tumors exhibiting increased macrophage density and TRAMP tumors exhibiting decreased macrophage density compared to age-matched wild type mice. The macrophage density and the adenocarcinoma cancer subtype of Hi-Myc appear to better mirror patient tumors, suggesting that the Hi-Myc model is the more appropriate in vivo TG model for studying TAMs and TME-targeted therapies.

DNA methylome, transcriptome, and prostate cancer prevention by phenethyl isothiocyanate in TRAMP mice.

Epigenetics/epigenomics has been shown to be involved in carcinogenesis. However, how the epigenome would be altered in the transgenic adenocarcinoma of the mouse prostate (TRAMP) cancer model and the effect of cancer chemopreventive phytochemical phenethyl isothiocyanate (PEITC) on the epigenome in TRAMP mice are not known. PEITC has been reported to reduce the risk of many cancers including prostate cancer (PCa). In this study, male TRAMP mice were fed a control diet or diet containing 0.05% PEITC from 8 weeks to 16 weeks. The tumor incidence was reduced in the PEITC diet (0/6) as compared with the control diet (6/7). RNA-sequencing (RNA-seq) analyses on nontumor and tumor prostatic tissues revealed several pathways like cell cycle/Cdc42 signaling, inflammation, and cancer-related signaling, were activated in prostate tissues of TRAMP mice but were reversed or attenuated in TRAMP mice fed with PEITC diet. DNA CpG methyl-seq analyses showed that global methylation patterns of prostate samples from TRAMP mice were hugely different from those of wild-type mice. Dietary PEITC partially reversed the global methylation changes during prostatic carcinogenesis. Integration of RNA-seq and DNA methyl-seq analyses identified a list of genes, including Adgrb1 and Ebf4, with an inverse regulatory relationship between their RNA expression and CpG methylation. In summary, our current study demonstrates that alteration of the global epigenome in TRAMP prostate tumor and PEITC administration suppresses PCa carcinogenesis, impacts global CpG epigenome and transcriptome, and attenuates carcinogenic pathways like cell cycle arrest and inflammation. These results may provide insights and epigenetic markers/targets for PCa prevention and treatment in human PCa patients.

Host versus cell-dependent effects of β-arrestin 1 expression in prostate tumorigenesis.

Prostate cancer (PCa) constitutes a serious health challenge and remains one of the main causes of cancer-related death among men. The more aggressive form of the disease has been attributed to androgen independence, resulting in a lack of response to androgen deprivation therapy and sustained activation of other growth pathways. The scaffold proteins β-arrestin 1 and 2 (βarr1 and βarr2), which are known to mediate G protein-coupled receptor desensitization and internalization, were also shown to modulate prostate tumorigenesis. βarr1 is significantly overexpressed (>4-fold) in PCa cells relative to βarr2. In this study, we investigated the effect of βarr1 overexpression in PCa development and progression using the mouse and human PCa cell xenografts, and autochthonous transgenic adenocarcinoma of the mouse prostate (TRAMP) models deficient in β-arrestin depletion of βarr1 in TRAMP mice (TRAMP/βarr1-/-) increased PCa growth and decreased overall survival relative to control TRAMP or TRAMP/βarr2-/- animals. Prostate tissues from TRAMP/βarr1-/- tumors displayed an increase in androgen receptor (AR) expression, whereas overexpression of βarr1 in TRAMP-C1 (TRAMP-C1-βarr1-GFP) which derived from TRAMP decreased AR expression, cell proliferation and tumor growth in nude mice xenografts, relative to control TRAMP-C1-GFP. Knockdown of βarr1 expression in human MDA PCa 2b cells (MDA PCa 2b-βarr1-/-) also decreased AR expression cell proliferation and tumor growth relative to control (MDA PCa 2b-Sham) cells. Interestingly, both TRAMP-C1-βarr1-GFP and MDA PCa 2b-βarr1-/- xenografts showed a decrease in AKT phosphorylation but an increase in MAPK activation. Altogether, the data indicate that the effect of βarr1 in modulating AR signaling to regulate PCa aggressiveness is cell and host autonomous.

Repurposing of the Antiepileptic Drug Levetiracetam to Restrain Neuroendocrine Prostate Cancer and Inhibit Mast Cell Support to Adenocarcinoma.

A relevant fraction of castration-resistant prostate cancers (CRPC) evolve into fatal neuroendocrine (NEPC) tumors in resistance to androgen deprivation and/or inhibitors of androgen receptor pathway. Therefore, effective drugs against both CRPC and NEPC are needed. We have previously described a dual role of mast cells (MCs) in prostate cancer, being capable to promote adenocarcinoma but also to restrain NEPC. This finding suggests that a molecule targeting both MCs and NEPC cells could be effective against prostate cancer. Using an in silico drug repurposing approach, here we identify the antiepileptic drug levetiracetam as a potential candidate for this purpose. We found that the protein target of levetiracetam, SV2A, is highly expressed by both NEPC cells and MCs infiltrating prostate adenocarcinoma, while it is low or negligible in adenocarcinoma cells. In vitro, levetiracetam inhibited the proliferation of NEPC cells and the degranulation of MCs. In mice bearing subcutaneous tumors levetiracetam was partially active on both NEPC and adenocarcinoma, the latter effect due to the inhibition of MMP9 release by MCs. Notably, in TRansgenic Adenocarcinoma of the Mouse Prostate (TRAMP) mice subjected to surgical castration to mimic androgen deprivation therapy, levetiracetam reduced onset and frequency of both high grade prostatic intraepithelial neoplasia, adenocarcinoma and NEPC, thus increasing the number of cured mice showing only signs of tumor regression. Our results demonstrate that levetiracetam can directly restrain NEPC development after androgen deprivation, and that it can also block adenocarcinoma progression through the inhibition of some MCs functions. These findings open the possibility of further testing levetiracetam for the therapy of prostate cancer or of MC-mediated diseases.

WHSC1/NSD2 regulates immune infiltration in prostate cancer

BackgroundImmunotherapy in prostate cancer (PCa) lags behind the progresses obtained in other cancer types partially because of its limited immune infiltration. Tumor-resident immune cells have been detected in the prostate,...

MINDIN Exerts Protumorigenic Actions on Primary Prostate Tumors via Downregulation of the Scaffold Protein NHERF-1.

Simple SummaryProstate cancer is one of the leading causes of death among men worldwide. Advanced prostate cancer is an incurable disease whose mechanisms of action are still not fully understood. Secretion of the matrix protein MINDIN has been associated with prostate tumor development towards advanced prostate cancer. We aimed to study the mechanisms whereby MINDIN promotes prostate cancer progression. Evaluation of human and mouse prostate cancer samples showed increased MINDIN expression associated with decreased expression of the adaptor protein Na+/H+ exchanger regulatory factor 1 (NHERF-1). We found that NHERF-1 was downregulated by MINDIN in prostate cancer, causing an increase in tumor cell migration and proliferation. These observations point to NHERF-1 as a key modulator of MINDIN actions on prostate cancer progression and suggest that both proteins could be potential targets for the development of future prostate cancer therapies.Advanced prostate cancer preferential metastasis to bone is associated with osteomimicry. MINDIN is a secreted matrix protein upregulated in prostate tumors that overexpresses bone-related genes during prostate cancer progression. Na+/H+ exchanger regulatory factor (NHERF-1) is a scaffold protein that has been involved both in tumor regulation and osteogenesis. We hypothesize that NHERF-1 modulation is a mechanism used by MINDIN to promote prostate cancer progression. We analyzed the expression of NHERF-1 and MINDIN in human prostate samples and in a premetastatic prostate cancer mouse model, based on the implantation of prostate adenocarcinoma TRAMP-C1 (transgenic adenocarcinoma of the mouse prostate) cells in immunocompetent C57BL/6 mice. The relationship between NHERF-1 and MINDIN and their effects on cell proliferation, migration, survival and osteomimicry were evaluated. Upregulation of MINDIN and downregulation of NHERF-1 expression were observed both in human prostate cancer samples and in the TRAMP-C1 model. MINDIN silencing restored NHERF-1 expression to control levels in the mouse model. Stimulation with MINDIN reduced NHERF-1 expression and triggered its mobilization from the plasma membrane to the cytoplasm in TRAMP-C1 cells. MINDIN-dependent downregulation of NHERF-1 promoted tumor cell migration and proliferation without affecting osteomimicry and adhesion. We propose that MINDIN downregulates NHERF-1 expression leading to promotion of processes involved in prostate cancer progression.

Kava root extracts hinder prostate cancer development and tumorigenesis by involvement of dual inhibition of MAO-A and LSD1.

Aim:Here, we aim to evaluate the chemopreventive efficacy of kava root extracts (KRE) in transgenic adenocarcinoma of the mouse prostate (TRAMP) mice and investigate potential molecular targets of kavalactones, the main components of kava.Methods:TRAMP mice were administrated with KRE formulated food for different periods of time, and then the incidences of high-grade prostatic intraepithelial neoplasia (HG-PIN) and adenocarcinomas and tumor burdens were compared between vehicle control and KRE food fed groups. In addition, the inhibitory effect of the KRE and kavalactones on monoamine oxidase A (MAO-A) and lysine-specific demethylase 1 (LSD1) enzyme activities were examined by commercially available inhibitor screening kits. Histone H3 lysine 9 dimethylation was also evaluated in prostate cancer cells and tumor tissues using Western blotting analysis.Results:Dietary feeding of 0.3% and 0.6% KRE to TRAMP mice from ages of 6 weeks to 12 weeks inhibited HG-PIN by 43.5% and 59.7%, respectively, and prostate adenocarcinoma by 53.5% and 66.4%, respectively. In addition, 0.6% KRE fed TRAMP mice from ages of 6 weeks to 24 weeks exhibited a significant reduction of genitourinary weight (a surrogate of tumor burden) by 54.5% and reduced body weight gain. Furthermore, the KRE and kavalactones showed a significant inhibition of LSD1 and MAO-A enzyme activities.Conclusion:Our results suggest that consumption of kava products through diet can delay prostate cancer development and progression and that kavalactones may be a new structure model for developing a potent dual inhibitor of LSD1 and MAO-A.

N6-methyladenosine RNA methylation regulators contribute to the progression of prostate cancer.

Prostate cancer (PCa) is one of the most common epithelial malignant tumors and the fifth leading cause of cancer death in men. An increasing number of studies have demonstrated that N6-methyladenosine (m6A) plays a crucial role in tumorigenesis and tumor development. However, little is known about the role and levels of common m6A regulators and m6A levels in PCa. In this study, we analyzed the characteristic expression of m6A regulators in PCa and castration-resistant prostate cancer (CRPC). UALCAN and cBioPortal were used to estimate the clinical value and genetic alterations of m6A regulators, respectively. The correlation between m6A regulators and androgen receptor (AR) was assessed using Gene Expression Profiling Interactive Analysis (GEPIA) by Pearson correlation statistics. Total m6A levels were detected in transgenic adenocarcinoma of the mouse prostate (TRAMP) mice and PCa cell lines. Results showed that the expression of methyltransferase-like 3 (METTL3) and YTH domain family members, namely, YTHDC2, YTHDF1, and YTHDF2 were generally upregulated in PCa, whereas those of fat mass and obesity-associated protein (FTO), AlkB homolog 5 (ALKBH5), and methyltransferase-like 14 (METTL14) were downregulated. The expression of METTL3, METTL14, Wilms' tumor 1-associating protein (WTAP), YTHDC2, YTHDF1, and YTHDF2 were remarkably higher in CRPC with lymph node metastasis than that in CRPC with bone metastasis, whereas ALKBH5, FTO, and YTHDF3 significantly decreased in CRPC with lymph node metastasis tissues. YTHDF1, YTHDF2, and YTHDC2 were positively correlated with the Gleason grades of PCa, and METTL14, FTO, and ALKBH5 were negatively associated with the Gleason classification. M6A regulators were positively correlated with AR. Patients with a genomic alteration of m6A were associated with poor disease-free survival (DFS). The total m6A levels in TRAMP mice increased dramatically compared with those in tumor-free mice, and m6A levels in LNCaP cell lines were higher than DU145 and PC3 cell lines. In summary, METTL3, METTL14, ALKBH5, FTO, YTHDC2, YTHDF1, and YTHDF2 were abnormally expressed in PCa and related to Gleason classification. Changes in m6A levels maybe contributed to the development and progression of PCa.

Roles of Interleukin-1 Receptor Antagonist in Prostate Cancer Progression.

Background: Inflammation is known to promote tumor formation and progression; however, we found a natural anti-inflammatory factor, interleukin (IL)-1 receptor antagonist (IL1RN), in a mouse transgenic adenocarcinoma of the mouse prostate (TRAMP)-C1-derived tumor microenvironment (TME). We sought to characterize the functions of the IL1RN-secreting cells in the TME. Methods: We compared tumors collected from two syngeneic mouse models and isolated tumor-infiltrating leukocytes (TILs) with different cluster of differentiation 11b (CD11b) statuses. We examined the proliferation functions of the TILs and the IL1RN using several approaches, including a colony-formation assay and DNA synthesis levels. Results: We demonstrated that CD11b-deficient TILs (TILs/CD11b−) secreted the IL1RN and promoted proliferation by analyzing conditioned media. In addition to mouse TRAMP-C1, proliferation functions of the IL1RN were confirmed in several human castration-resistant prostate cancer (CRPC) cell lines and one normal epithelial cell line. The androgen-sensitive lymph node carcinoma of the prostate (LNCaP) cell line showed cytotoxic responses to IL1β treatment and androgen-dependent regulation of IL-1 receptor type 1 (IL1R1), while the C4-2 CRPC cell line did not. IL1RN rescued LNCaP cells from the cytotoxic effects of IL1β/IL1R1 signaling. Conclusions: Our results support TILs/CD11b− cells being able to protect androgen-dependent cells from inflammatory damage and promote the malignant progression of prostate cancers partly through the IL1RN in the TME.

A rise in T3/T4 ratio reduces the growth of prostate tumors in a murine model.

Thyroxine (T4) promotes cell proliferation and tumor growth in prostate cancer models, but it is unknown if the increase in the triiodothyronine (T3)/T4 ratio could attenuate prostate tumor development. We assessed T3 effects on thyroid response, histology, proliferation, and apoptosis in the prostate of wild-type (WT) and TRAMP (transgenic adenocarcinoma of the mouse prostate) mice. Physiological doses of T3 were administered in the drinking water (2.5, 5 and 15 µg/100 g body weight) for 6 weeks. None of the doses modified the body weight or serum levels of testosterone, but all of them reduced serum T4 levels by 50%, and the highest dose increased the T3/T4 ratio in TRAMP. In WT, the highest dose of T3 decreased cyclin D1 levels (immunohistochemistry) but did not modify prostate weight or alter the epithelial morphology. In TRAMP, this dose reduced tumor growth by antiproliferative mechanisms independent of apoptosis, but it did not modify the intraluminal or fibromuscular invasion of tumors. In vitro, in the LNCaP prostate cancer cell line, we found that both T3 and T4 increased the number of viable cells (Trypan blue assay), and only T4 response was fully blocked in the presence of an integrin-binding inhibitor peptide (RGD, arginine-glycine-aspartate). In summary, our data show that the prostate was highly sensitive to physiological T3 doses and suggest that in vivo, an increase in the T3/T4 ratio could be associated with the reduced weight of prostate tumors. Longitudinal studies are required to understand the role of thyroid hormones in prostate cancer progression.

Galectin-3 in Prostate Cancer Stem-Like Cells Is Immunosuppressive and Drives Early Metastasis.

Galectin-3 (Gal-3) is an extracellular matrix glycan-binding protein with several immunosuppressive and pro-tumor functions. The role of Galectin-3 in cancer stem-like cells (CSCs) is poorly investigated. Here, we show that prostate CSCs also colonizing prostate-draining lymph nodes of transgenic adenocarcinoma of the mouse prostate (TRAMP) mice overexpress Gal-3. Gal-3 contributes to prostate CSC-mediated immune suppression because either Gal-3 silencing in CSCs, or co-culture of CSCs and T cells in the presence of the Gal-3 inhibitor N-Acetyl-D-lactosamine rescued T cell proliferation. N-Acetyl-D-lactosamine also rescued the proliferation of T cells in prostate-draining lymph nodes of TRAMP mice affected by prostate intraepithelial neoplasia. Additionally, Gal-3 impacted prostate CSC tumorigenic and metastatic potential in vivo, as Gal-3 silencing in prostate CSCs reduced both primary tumor growth and secondary invasion. Gal-3 was also found expressed in more differentiated prostate cancer cells, but with different intracellular distribution as compared to CSCs, which suggests different functions of Gal-3 in the two cell populations. In fact, the prevalent nuclear and cytoplasmic distribution of Gal-3 in prostate CSCs made them less susceptible to apoptosis, when compared to more differentiated prostate cancer cells, in which Gal-3 was predominantly intra-cytoplasmic. Finally, we found Gal-3 expressed in human and mouse prostate intraepithelial neoplasia lesions and in metastatic lymph nodes. All together, these findings identify Gal-3 as a key molecule and a potential therapeutic target already in the early phases of prostate cancer progression and metastasis.

A simple quantitative PCR assay to determine TRAMP transgene zygosity

BACKGROUND.The TRansgenic Adenocarcinoma of the Mouse Prostate (TRAMP) model remains one of the most widely used transgenic mouse models of prostate cancer. This is due to its ability to recapitulate with ~100% penetrance multiple aspects of the human disease such as prostatic intraepithelial neoplasia lesions, invasive carcinoma, progression to castration-resistant prostate cancer including aggressive neuroendocrine prostate cancer and metastasis. Despite its popularity, the use of TRAMP mice is limited/slowed by the inability to distinguish the zygosity of the TRAMP transgene. This is especially true for breeding strategies implementing multiple crosses and alleles and when the rapid generation of large animal cohorts with the desired genotype is needed.METHODS.We developed a quantitative PCR (qPCR) approach to determine the relative TRAMP transgene copy number of mice.RESULTS.This method was validated by three independent laboratories across two institutions, which successfully identified the genotype of the mice 98.2% of the time (165/168) in the first attempt. The genotypes of the uncertain mice were correctly identified in the repeated experiments.CONCLUSIONS.We develop the first straightforward, quantitative PCR (qPCR) approach to reliably determine the TRAMP transgene zygosity. The development of this qPCR-based genotyping method enables researchers to streamline breeding strategies when creating complex genetic mouse models involving TRAMP mice; thus, ultimately reducing the required animal numbers, cost, and investigator time.

Ultrasound-Mediated Delivery of Chemotherapy into the Transgenic Adenocarcinoma of the Mouse Prostate Model

Ultrasound (US) in combination with microbubbles (MB) has had promising results in improving delivery of chemotherapeutic agents. However, most studies are done in immunodeficient mice with xenografted tumors. We used two phenotypes of the spontaneous transgenic adenocarcinoma of the mouse prostate (TRAMP) model to evaluate if US + MB could enhance the therapeutic efficacy of cabazitaxel (Cab). Cab was either injected intravenously as free drug or encapsulated into nanoparticles. In both cases, Cab transiently reduced tumor and prostate volume in the TRAMP model. No additional therapeutic efficacy was observed combining Cab with US + MB, except for one tumor. Additionally, histology grading and immunostaining of Ki67 did not reveal differences between treatment groups. Mass spectrometry revealed that nanoparticle encapsulation of Cab increased the circulation time and enhanced the accumulation in liver and spleen compared with free Cab. The therapeutic results in this spontaneous, clinically relevant tumor model differ from the improved therapeutic response observed in xenografts combining US + MB and chemotherapy.

Dietary Tomato or Lycopene Do Not Reduce Castration-Resistant Prostate Cancer Progression in a Murine Model

Dietary tomato products or lycopene protect against prostate carcinogenesis, but their impact on the emergence of castration-resistant prostate cancer (CRPC) is unknown. We hypothesized that tomato or lycopene products would reduce the emergence of CRPC. Transgenic adenocarcinoma of the mouse prostate (TRAMP) mice were castrated at 12-13 wk and the emergence of CRPC was monitored by ultrasound in each study. In Study 1, TRAMP mice (n=80) were weaned onto an AIN-93G-based control diet (Con-L, n=28), a 10% tomato powder diet (TP-L, 10% lyophilized w/w, n=26), or a control diet followed by a tomato powder diet after castration (TP-Int1, n=26). In Study 2, TRAMP mice (n=85) were randomized onto a control diet with placebo beadlets (Con-Int, n=29), a tomato diet with placebo beadlets (TP-Int2, n=29), or a control diet with lycopene beadlets (Lyc-Int, n=27) following castration (aged 12 wk). Tumor incidence and growth were monitored by ultrasound beginning at an age of 10 wk. Mice were euthanized 4 wk after tumor detection or aged 30 wk if no tumor was detected. Tissue weights were compared by ANOVA followed by Dunnett's test. Tumor volumes were compared using generalized linear mixed model regression. Ultrasound estimates for the in vivo tumor volume were strongly correlated with tumor weight at necropsy (R2=0.75 and 0.94, P <0.001 for both Studies 1 and 2, respectively). Dietary treatments after castration did not significantly impact cancer incidence, time to tumor detection, or final tumor weight. In contrast to studies of de novo carcinogenesis in multiple preclinical models, tomato components had no significant impact on the emergence of CRPC in the TRAMP model. It is possible that specific mutant subclones of prostate cancer may continue to show some antiproliferative response to tomato components, but further studies are needed to confirm this.

Prevention of Prostate Cancer in Transgenic Adenocarcinoma of the Mouse Prostate Mice by Yellow Passion Fruit Extract and Antiproliferative Effects of Its Bioactive Compound Piceatannol.

Piceatannol (PIC), a polyphenol presents in many vegetables and fruits including yellow passion fruit extract (PFE; Passiflora edulis), has anti-cancer activity, but its molecular targets are still poorly understood. The aims of this study were to investigate the molecular mechanistic actions of PIC in prostate cancer cell lines and to test if the extract from PFE rich in PIC can affect the growth of prostate cancer cells in the Transgenic Adenocarcinoma of the Mouse Prostate (TRAMP) model. The PC-3, 22Rv1, LNCaP, and VCaP prostate cancer cells were exposed to PIC (10-40 μM), and cell viability, lactate measurement, Western blot, and flow cytometric analyses were performed. For an in vivo experiments, eight-week-old TRAMP mice (n = 10 per group each) received an aqueous extract of PFE containing 20 mg of PIC/kg or water (control group) by gavage for 4 or 10 weeks for further analyses. PIC treatment concentration- and time-dependently reduced viability of all cell lines tested. 22Rv1 and LNCaP cells treated with PIC did not exhibit any significant alteration in the intracellular accumulation of lactate. PIC treatment caused G0/G1 phase cell cycle arrest and induction of apoptosis in both LNCaP and 22Rv1 cells. PIC-treated cells exhibited altered protein levels of p53, p21, cyclin D1, and cyclin-dependent kinase 4 (cdk4). The short and long-term PFE treatments also affected p21, cyclin D1 and cdk4 and delayed disease progression in TRAMP, with a decreased incidence of preneoplastic lesions. In conclusion, PIC apparently does not alter glucose metabolism in prostate cancer cells, while cell cycle arrest and p53 modulation are likely important in anti-cancer effects of PIC alone or as a food matrix byproduct in prostate cancer cells, especially those with an androgen-dependent phenotype.

Dietary Tomato Varieties Similarly Inhibit Prostate Carcinogenesis in the TRAMP Model in Association with Distinct Transcriptomic and Metabolomic Profiles

Abstract Objectives Lycopene intake is associated with reduced risk of prostate cancer, especially lethal disease. Tangerine tomatoes contain highly bioavailable lycopene isomers, compared to red tomatoes, but impact of isomers on cancer preventive bioactivity are unknown. Our goals are: (1) to determine if feeding tomato containing diets with differing lycopene isomers inhibit transgenic adenocarcinoma of the mouse prostate (TRAMP) carcinogenesis, and (2) to determine key early metabolic and transcriptional pathways through which tomatoes act to prevent carcinogenesis. Methods We examine prostate carcinogenesis in the TRAMP model, comparing two tomatoes with distinct lycopene isomer profiles: all-trans-lycopene-rich red tomatoes and cis-lycopene-isomer-rich tangerine tomatoes. Weanling TRAMP and wild type (WT) mice were fed AIN-93 G control, 10% tangerine tomato + AIN-93 G (w/w), or 10% red tomato + AIN-93 G (w/w) diet until 10 or 18 wks. At 10 wks., prostate RNA-seq and plasma metabolomics were performed on TRAMP and WT samples. At 18 wks., plasma carotenoid analysis and histopathology was performed on TRAMP mice. Results At 18 wks., plasma lycopene concentrations were 2.84-fold greater in tangerine tomato-fed mice than red tomato-fed mice (p &amp;lt; 0.0001), yet both red and tangerine tomato diets similarly prevent carcinoma incidence compared to the control diet by 43% and 36% respectively (p &amp;lt; 0.001, both vs. control). Our investigation of early carcinogenesis (10 wks.) shows that both tomato diets similarly impact the plasma metabolome, and we define prostate transcriptomic profiles mediated by TRAMP genotype, such as inflammation- and immune-regulated pathways, that are inhibited by dietary tomato. We identify an inflammatory gene panel (Olr1, Il1a, Cscl9, and Ccl22) which is inhibited by tomato diets. In a human prostate cancer database, higher expression of this gene panel is associated with a more aggressive phenotype. Conclusions Together, our results implicate red and tangerine tomatoes as potentially beneficial for the inhibition of early prostate carcinogenesis through the modulation of transcriptional programs centered on inflammation and the immune response. Our findings support efforts to test novel tomato products for the inhibition of human prostate carcinogenesis. Funding Sources AICR, NIH P30, USDA NNF.

Can Tomato Powder Reduce Radiation-Induced Effects in a Murine Model of Prostate Cancer?

Abstract Objectives Tomatoes contain carotenoids and other potent antioxidants that may protect the surrounding tissue from the detrimental effects of external beam radiation therapy, while reducing rates of prostate carcinogenesis. The objective of this study was to determine whether dietary lyophilized tomato paste (TP) alters early inflammatory and oxidative events following a single dose of radiation and leads to a more successful therapeutic outcome. Methods Male Transgenic Adenocarcinoma of the Mouse Prostate (TRAMP) mice (n = 76) were provided a powdered AIN-93 G diet (Control) or a modified AIN-93 G diet containing 10% TP (w/w) at 4 weeks of age. Mice were monitored by ultrasound for in vivo tumor detection and 3-D volumetric measurement biweekly. Once tumors reached a volume of 1000 mm3, the caudal half of the mouse was irradiated with 7.5 gy (Rad, n = 18–19 per diet) or 0 gy (sham, n = 16–20 per diet) with a Cobalt-60 source. Mice were euthanized 24 hours after radiation or sham treatment. Antioxidants (carotenoids and α-tocopherol) were measured by high performance liquid chromatography (HPLC) in the serum, tumor, prostate, and liver. Sections of tumor, liver, kidneys, bladder, lymph, bladder and intestines were stained by hematoxylin and eosin (H&amp;E) and cleaved-caspase 3 were assessed for radiation-induced changes and apoptosis. Inflammatory markers (C-reactive protein, IL-6, IL-17A, TNFα, IFNγ, and IL-10) were measured in serum, liver, prostate, tumor, and epididymal adipose tissues by ELISA. Results This study is the first to explore the effects of TP on the tumor microenvironment following irradiation. Initial results suggest that TP consumption does not alter circulating or tissue (liver and prostate) concentrations of inflammatory markers (C-reactive protein, TNFα, IFNγ, IL-6, IL-17, or IL-10). We hypothesize that TP-Rad will maintain similar levels of circulating concentrations of antioxidants (carotenoids and α-tocopherol) compared to sham-treated mice. Additionally, we hypothesize that TP will reduce markers of cell damage in surrounding tissues. Conclusions This study will provide important preclinical data to inform future clinical trials evaluating approaches to lessen extra-prostatic damage from radiation therapy and thus improve therapeutic outcomes. Funding Sources This work was supported by USDA NIFA ILLU-971–334.

Therapeutic ISCOMATRIX™ adjuvant vaccine elicits effective anti-tumor immunity in the TRAMP-C1 mouse model of prostate cancer.

Cancer vaccine development has proven challenging with the exception of some virally induced cancers for which prophylactic vaccines exist. Currently, there is only one FDA approved vaccine for the treatment of prostate cancer and as such prostate cancer continues to present a significant unmet medical need. In this study, we examine the effectiveness of a therapeutic cancer vaccine that combines the ISCOMATRIX™ adjuvant (ISCOMATRIX) with the Toll-like receptor 3 agonist, polyinosinic–polycytidylic acid (Poly I:C), and Flt3L, FMS-like tyrosine kinase 3 ligand. We employed the TRAMP-C1 (transgenic adenocarcinoma of the mouse prostate) model of prostate cancer and the self-protein mPAP (prostatic acid phosphatase) as the tumor antigen. ISCOMATRIX™–mPAP–Poly I:C–Flt3L was delivered in a therapeutic prime-boost regime that was consistently able to achieve complete tumor regression in 60% of animals treated and these tumor-free animals were protected upon rechallenge. Investigations into the underlying immunological mechanisms contributing to the effectiveness of this vaccine identified that both innate and adaptive responses are elicited and required. NK cells, CD4+ T cells and interferon-γ were all found to be critical for tumor control while tumor infiltrating CD8+ T cells became disabled by an immunosuppressive microenvironment. There is potential for broader application of this cancer vaccine, as we have been able to demonstrate effectiveness in two additional cancer models; melanoma (B16-OVA) and a model of B cell lymphoma (Eµ-myc-GFP-OVA).Electronic supplementary materialThe online version of this article (10.1007/s00262-020-02597-6) contains supplementary material, which is available to authorized users.

Abstract A69: Elucidating the cell type-specific mechanisms of the Ron receptor in the prostate tumor microenvironment

Abstract The incidence of advanced prostate cancer (PCa) in American men has grown by 72% within the last decade, yet current treatments fail to effectively treat advanced disease. We study the Ron receptor tyrosine kinase as a novel target for PCa treatment. Ron is primarily expressed in macrophages and epithelial cells and is found overexpressed in PCa. Ron expression increases with disease severity in humans and mouse models, suggesting Ron drives progression to advanced PCa. Our laboratory has shown that loss of Ron signaling in prostate epithelial cells or in myeloid cells markedly reduces prostate tumor growth and modulates the tumor microenvironment, particularly the functions of macrophages and CD8+ T cells. Thus, we hypothesize that the Ron receptor utilizes cell type-specific mechanisms to suppress the antitumor immune response. However, our previous studies were limited because they were performed separately in different orthotopic models. Therefore, we employed the well-established Transgenic Adenocarcinoma of the Mouse Prostate (TRAMP) PCa mouse model to study loss of Ron signaling in either cell type in a single autochthonous model. We used Cre-Lox technology to generate TRAMP mice containing conditional deletion of Ron signaling in prostate epithelial cells or in myeloid cells. At 30 weeks of age, prostate tumors are harvested and analyzed by weight, immunohistochemical staining, quantitative PCR, Western blot, and flow cytometry. To assess the effects of Ron modulation in each cell type and interrogate the interaction between tumor cells and macrophages, we perform in vitro co-culture assays utilizing an established prostate cancer epithelial cell line derived from the TRAMP model and bone marrow-derived macrophages. We observe that Ron signaling in either cell type is critical for prostate tumor growth in TRAMP mice. Furthermore, loss of Ron in either cell type leads to increased macrophage and CD8+ T-cell tumor infiltration, and our in vitro data show that loss of Ron in either cell type suppresses antitumor M1 macrophage activation and promotes tumor-supporting M2 macrophage activation. Additionally, preliminary data suggest loss of Ron in either cell type leads to increased activation of CD8+ tumor-infiltrating lymphocytes. Overall, our data suggest the Ron receptor coordinates immunosuppressive mechanisms in both the malignant tumor cells and the host macrophages to dampen antitumor immunity and promote prostate cancer. These studies implicate Ron targeting as a powerful therapeutic tool with broad utility for understanding and refining therapeutic strategies to treat advanced PCa. Citation Format: Camille Sullivan, Nicholas E. Brown, Susan E. Waltz. Elucidating the cell type-specific mechanisms of the Ron receptor in the prostate tumor microenvironment [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr A69.

Extract From Yellow Passion‐Fruit (passilora edulis) Inhibits Prostate Cancer Cell Proliferation By TLR4/NFkB Pathway Regulation

The yellow passion‐fruit (passiflora‐edulis) is rich in piceatannol (PIC), a polyphenolic and resveratrol analog known by its beneficial effects on health such as anti‐inflammatory anti‐cancer properties. The present study aimed to investigate the passion‐fruit extract (PFE) mechanistic of action in prostate cancer (PCa) cell lines with different genetic backgrounds and in the transgenic adenocarcinoma of the mouse prostate (TRAMP). For in vitro experiments, LNCaP (androgen‐responsive) and PC‐3 (androgen‐independent) cells were treated with different doses of PFE (125–500 μg/mL) and used for cell viability assay and western blotting analysis. For in vivo experiments, TRAMP mice were gavaged with 20mg/Kg of PIC contained in the PFE during 4 or 10 weeks of treatment. The ventral prostate was collected for light microscopy, immunohistochemistry and western blotting analysis. Because inflammation is intrinsically evolved with prostate alterations, like hormonal imbalance and cell survival, we focused on if PFE could affect these pathways. PFE treatment caused a significant reduction of cell viability in both cell lines tested, as well as decreased nuclear factor kappa B (NFκB) and toll‐like receptor 4 protein level. Interestingly, LNCaP cells were more sensitive to the PFE action in all experiments and we verified that the androgen receptor was markedly reduced by the treatment in these cells. PFE delayed CaP progression in the TRAMP model in both periods of treatment, significantly decreasing high‐grade prostatic intraepithelial neoplasia and well‐differentiated adenocarcinoma. These results were confirmed by the decrease of proliferating cell nuclear antigen immunostaining. Also, treatment with PFE reduced inflammation markers such as tumor necrosis factor‐alpha (TNF‐α), NFκB, and modulated negatively cell cycle regulatory protein levels and signal transducer and activator of transcription 3. Therefore, the results herewith showed that PFE was able to modulate disease progression through the inhibition of the inflammatory pathways, delay of the cell cycle, especially in the hormone‐dependent profile, demonstrating its chemopreventive and therapeutic potential in PCa.Support or Funding InformationSao Paulo Research Foundation ( Number: 2017/01573‐5)